Stator for rotaty electrical equipment

ABSTRACT

A rotating electrical machine having cooperating rotor and stator, one of which forms a plurality of pole teeth around which individual coils are wound. The coils are connected in a number depending upon the phase and number of poles and the connected coils of each phase are spaced from each other. Crossover wires connect these coil windings of each phase and the crossover wires are affixed by bonding to outstanding tabs that are formed on the outermost laminations of the assembly. This reduces hand labor and insures that the crossover wires will not interfere with other components of the machine or associated driving or driven structures.

BACKGROUND OF INVENTION

[0001] This invention relates to an improved stator for rotaryelectrical equipment and more particularly to an improved coil windingarrangement for multi-phase equipment of this type.

[0002] In connection with rotating electrical machines, it is commonpractice to employ a series of circumferential spaced permanent magnetswhich cooperate with pole teeth around which coil windings are formed inorder to either produce electrical power when the machine is a generatoror to provide a driving force when the machine is a motor. The coilwindings are wound around the pole teeth. When multi-phase winding isemployed, certain coils are placed on adjacent pole teeth and then anumber of coils is skipped for each phase before the next series ofcoils is wound for the phase.

[0003] A wire called a “crossover wire” connects the groups of coilwindings of each phase.

[0004] A disadvantage with this type of construction is that thecrossover wires must be dealt with. That is, they must be positioned insuch a way so that the crossover wires are not accidentally placed in aposition where they may be damaged. This requires hand placement of thecrossover wires and greatly impedes the ability to expedite production.It is therefore the practice to provide some form of clampingarrangement that fixes these crossover wires to the stator core or tothe housing of the machine, thus requiring manual labor.

[0005] Also, there is a problem in connection with the tying down orholding of these crossover wires so they do not become displaced whenthe machine is on operation. This also necessitates the tying down ofthe crossover wires.

[0006] It is, therefore, a principal object to this invention to providean improved rotating electrical machine having phase windings andwherein the crossover wires connecting the coils of the individualphases are rigidly held in position and without manual operation.

[0007] It a further object to this invention to provide an improved coilwinding arrangement for a multi-phase rotating electrical machine.

SUMMARY OF INVENTION

[0008] This invention is adapted to be embodied in a coil windingarrangement for a rotating electrical machine. The winding arrangementis comprised of a core comprised of a plurality of laminated plates eachhaving a cylindrical portion from which a plurality of circumferentiallyspaced, pole tooth forming portions extend in a generally radialdirection. The plurality of laminated plates are held in abuttingrelation with their pole tooth forming portions aligned to form aplurality of cores. A plurality of phase windings are wound on the core.Each of these phase windings are wound around a series of the coresarranged in groups of adjacent cores. The groups of cores are spaced bycores around which other of the phase windings are wound. The windingsof each group of each of the phases are connected to each other bycrossover wires to provide the electrical connection between the coilsof the groups of adjacent cores. An axial outermost of the laminatedplates is formed with outstanding tabs at circumferentially spacedlocations against which said crossover wires lie.

[0009] In accordance with another feature of the invention, thecrossover wires are adhesively bonded to the tabs by an insulatingmaterial.

BRIEF DESCRIPTION OF DRAWINGS

[0010]FIG. 1 is a cross sectional view taken through a portion of aninternal combustion engine associated with a rotating electrical machineconstructed in accordance with an embodiment of the invention.

[0011]FIG. 2 is an end elevational view of the rotating machine andshowing the coil winding arrangement for a single phase.

[0012]FIG. 3 is a view looking in the same direction as FIG. 2 but showsall of the phases of the winding.

[0013]FIG. 4 is a view, in part similar to FIGS. 2 and 3, but shows thefinished coil winding arrangement.

[0014]FIG. 5 is a cross sectional view taken along the line 5-5 of FIG.4 but with the windings eliminated.

[0015]FIG. 6 is a partially exploded perspective view showing thearmature core.

[0016]FIG. 7 is a view looking in the same direction as FIG. 2 and inpart similar to this figure but showing another embodiment of theinvention.

DETAILED DESCRIPTION

[0017] Referring now in detail to the drawings and initially primarilyto FIG. 1, an embodiment of the invention is shown as associated with aninternal combustion engine, indicated generally by the reference numeral11. The invention is shown in conjunction with an internal combustionengine 11 because this is a typical environment in which the inventioncan be utilized although the use is not so limited.

[0018] One reason why this invention has particular utility withinternal combustion engines is that it permits a compact rotatingelectrical machine and one, which can be machined and produced in highproduction volumes at a low cost because the amount of manual laborinvolved is substantially minimized.

[0019] Only a portion of the engine 11 is shown and where any details ofthe engine are not illustrated or described, those skilled in the artwill readily understand how the invention can be applied in this type ofenvironment.

[0020] In this embodiment, a rotating electrical machine, indicatedgenerally by the reference numeral 12 is provided in an area forwardlyof the engine crankcase, indicated by the reference numeral 13, and isclosed by a front cover 14 that is fixed to a front wall of a crankcase13. The crankcase 13 provides an anti-friction bearing 15 for journalinga crankshaft 16 of the engine 11. The crankshaft 16 is of the split typeand is provided with one or more throws on which the big ends ofconnecting rods 17 are journalled by roller or needle type bearings 18.The connecting rods 17 are connected at their upper ends to pistons,which reciprocate in cylinder bores 19 of the engine.

[0021] A front wall 21 of the crankcase 13 has a nose portion 22 thatforms the carrier for the stator, indicated generally by the referencenumeral 23, of the rotating electrical machine 12. In this specificembodiment, the rotating electrical machine 12 is a generator but itshould be understood by those skilled in the art that it also could be amotor for starting the engine 11.

[0022] A rotor assembly 24 of the rotating electrical machine 12 has akeyed connection to a nose portion 25 of the crankshaft 16. This rotoris of an inverted cup shape and carries a number of circumferentiallyspaced permanent magnets 26 opposite of alternating polarity around itscircumference. These magnets 26 cooperate with coil windings 27 formedon pole cores or teeth 28 of the stator 23.

[0023] A cooling fan 29 draws cooling air through an inlet opening 31for cooling the generator 12.

[0024] Referring now additionally to FIGS. 2 and 3, as noted the rotor24 is fixed for rotation with the crankshaft 16. To this end the rotor24 has a boss portion, which comprises a boss section 32 fixed to acrankshaft 16 of the engine 11. The permanent magnets 26 are fixed to acup shaped member 33 fixed to a flange of the boss section 32 by rivetfasteners 34.

[0025] The permanent magnets 26 are magnetized such that they have 2npolarities alternating in the circumferential direction. In this examplen=8, and the number M of magnetic poles is 2n=16. Regarding the numberof magnetic poles arranged in the direction of rotation of the rotor,since North (N) poles and South (S) poles of the same number aredisposed at regular intervals in the circumferential direction, thenumber of magnetic poles is 2n. The number P of teeth or cores (magneticpole teeth) 28 of the stator core is 3m for a three-phase generator,where n, m are positive The stator 23 is made of laminated thin steelplates as will be described in more detail later by reference to FIGS. 5and 6. The stator and its individual plates are comprised of continuouscylindrical portions 35 from which the pole cores or teeth 28 extendoutwardly in a radial direction and on which the coils 27 are wound. Thestator 23 has eighteen teeth 28, and thus 3×m=18, which gives m=6.

[0026] The coils 27 have U-, V- and W-phases. The coils 27(U), 27(V),27(W) of each phase are wound on adjacent three teeth in series as seenin FIGS. 2 and 3. Coils 27 a, 27 b, 27 c on adjacent three teeth areconnected by a crossover wire 36 to coils 27 d, 27 e, 27 f on adjacentthree teeth at a symmetrical position six teeth ahead. Of course thecoils 27 and their crossover wires 36 are preferably formed from acontinuous strand of wire although they are referred to separately.

[0027] The winding direction of each coil 27 a-27 f is made so thatinduced voltage of each coil 27 a-27 f has the same polaritycorresponding to polarity change of the permanent magnets 26 to whicheach coil 27 a-27 f faces.

[0028] In this embodiment, the number of teeth or cores 28 of the stator23 is 3m, that of magnetic poles of the rotor 24 is 2n, and the numbers3m, 2n are set such that 2/n is not to be an integer so that inducedvoltages of a plurality of teeth forming a voltage of the same phasehave the same polarity and different phases. As a result, driving torqueis decreased, enabling size reduction of the driving engine, and asmooth output waveform is effected, improving efficiency of powergeneration, as is disclosed in Laid Open Japanese Patent Application Hei11-288449 filed by the present applicant (corresponding U.S. Ser. No.09/628,755, filed Jul. 31, 2001), and the description thereof will berepeated here.

[0029] In this embodiment, neodymium-iron-boron permanent magnets 26 areused, having 2n=sixteen poles, and the number of teeth 28 is eighteen,that is, 3m=18.

[0030] Therefore, n=8 and m=6. In this case, an angle (pitch) θ1 betweenthe magnets 26 is θ1=π/2n (radian)=22.5°, and an angle (pitch angle) θ2of the teeth 28 is θ2=2π/3n (radian)=20°.

[0031] Since the number of teeth 28 is a multiple of two, the coils 27of the same phase (U-phase in FIG. 2) are divided into two groups, thatis, symmetrical groups 27 a-27 c and 27 d-27 f of m/2=three poles each,and each coil group is wound on adjacent three teeth 28 in series. Sincethe adjacent teeth 28 face to magnets 26 of different polarities, thecoils are wound on the teeth alternately in the opposite directions sothat induced voltages of the coils are not reversed to each other. Inthis embodiment, an angle by which 2/m=three teeth 28 are offset fromthree magnets 26, or a phase difference θ, is Δθ×(m/2−1)=Δθ×2, and thusΘ=Δθ×2<θ½.

[0032] As has been previously noted, the core of the stator 23 is madeup of laminated steel plates. That construction will now be described byprinciple reference to FIGS. 5 and 6. The laminated thin steel plates ofthe stator 23 are indicated generally by the reference numeral 37. Eachplate 37 has a continuous cylindrical section 35 from which the poles orteeth 28 radiate. These plates 37 comprise inner thin plates 37bsandwiched by axial outermost upper and lower two plates 37a. Except ashereinafter noted, the plates 37 b and 37 a are of the same shape. Thetip ends of the teeth 28 are stamped out in the shape of a letter T.

[0033] The outermost two thin plates 37 a have tabs 38 bent at their tipends at right angles (in the direction of lamination), as shown in FIG.6, so that the tabs 38 overlie the T-shaped tip portions of the tip endsof the teeth 28 of the middle plates 37 b.

[0034] Near the bottoms of slots between the teeth 28 of the outerplates 37 a are formed further tabs 39 extending axially outwardly inthe direction of lamination. The thin plates 37 a, 37b are laminated andfastened together with their pole teeth 28 aligned by a plurality ofrivets 41 (FIGS. 3, 4 and 6). In addition the attached assembly on thestator 23 is affixed to the crankcase nose portion 22 by a mountingplate 42 (FIG.1) by fasteners 43 that pass through openings 44 in thestator 23.

[0035] After the plates 37 a, 37 b are laminated and fastened togetherwith the rivets 41, this assembly is coated with insulating material, atleast in the region including the teeth 28 and the tabs 39, that is, thearea other than the cylindrical portion 35 of the stator 23.

[0036] The coil wire is wound around over the insulating material, asshown in FIG. 3. In this case, a crossover wire 36 (36(U), 36(V), 36(W))of each phase is set on the outside circumferential side of the tabs 39of the outermost thin plate 37 a, as shown in FIG. 4.

[0037] As a result, for the U-phase, circumferentially adjacent threecoils shown by symbols Al, A2, A3 and three coils at a diagonal positionshown by symbols A4, AS, A6 are formed. Likewise, for the V-phase, coilsB1, B2, B3 and coils B4, B5, B6 at a diagonal position, and further forthe W-phase, coils C1, C2, C3 and coils C4, C5, C6 at a diagonalposition are formed. In this case, the crossover wire 36 (36(U), 36(V),36(W)) of each phase is wired along the outside circumference of thetabs 39.

[0038] The stator 23 having coils 27 wound on all teeth 28 is thencoated with insulating material. That is, coils wound on the teeth 28,and crossover wires 36 set outside the tabs 39, are coated with theinsulating material and thus, the crossover wires 36 are adhesivelybonded to the tabs 39 by the insulating material thus restricting theirfree movement. This final assembly is shown in FIG. 4.

[0039]FIG. 7 is a front view of a rotating electrical machineconstructed in accordance with another embodiment of the invention. Thisembodiment is made in the same manner as that of FIGS. 1 -6 and differsonly in the number of pole teeth and permanent magnets thus a completedescription of the structure is not required.

[0040] In this embodiment the number M of magnetic poles of a rotor 24Ais twelve and the number P of teeth of a stator 23A is eighteen. Coils27A of each of U-, V- and W-phases are wound on every four teeth A inseries. In this case, every four teeth 28 on which coils 27A of the samephase are wound, will face to magnetic poles 26 of the same polarity atthe same electrical angle. Also, crossover wires 36A connecting everyfour coils of the same phase are set on the outside circumferential sideof the tabs (not shown) provided on the outermost layer of the stator.As a result, the crossover wires 36A are prevented from being movedradially inwardly of the tabs. In addition, the coils 27A and crossoverwires 36A are coated with insulating material for fixing, restrictingfree movement of the crossover wires 36A.

[0041] Thus, from the foregoing description it should be readilyapparent that the described embodiments of the invention provide a verysimple arrangement for a rotating electrical machine wherein manuallabor is substantially reduced in assembly and wherein the crossoverwires are automatically and permanently bonded so as to avoid theirbeing positioned where they can obstruct the remainder of the machine orother components which may be associated with it. In addition, thisprovides a very neat assembly and insures long life without trouble. Ofcourse, the embodiments described are only preferred embodiments of theinvention and various changes and modifications may be made withoutdeparting from the spirit and scope of the invention, as defined by theappended claims.

1. A coil winding arrangement for a rotating electrical machinecomprised of a core comprised of a plurality of laminated plates eachhaving a cylindrical portion from which a plurality of circumferentiallyspaced, pole tooth forming portions extend in a generally radialdirection, said plurality of laminated plates being in abutting relationwith their pole tooth forming portions aligned to form a plurality ofcores, a plurality of phase windings, each of said plurality of phasewindings being wound around a series of said cores arranged in groups ofadjacent cores, said groups of cores being spaced by cores around whichother of said phase windings are wound, the windings of each group ofeach of said phases being connected to each other by crossover wires toprovide the electrical connection between the coils of said groups ofadjacent cores, and an axial outermost of said laminated plates beingformed with outstanding tabs at circumferentially spaced locationsagainst which said crossover wires lie.
 2. A coil winding arrangement asset forth in claim 1, wherein the crossover wires are ashesively bondedto the outstanding tabs.
 3. A coil winding arrangement as set forth inclaim 2, wherein the adhesive bond is formed by an insulating material.4. A coil winding arrangement as set forth in claim 3, wherein theinsulating material is applied to the laminated plates before thewinding and to the coils and crossover wires after winding.
 5. A coilwinding arrangement as set forth in claim 1, wherein the pole teethextend radially outwardly from the cylindrical portion and the tabs areformed adjacent said pole teeth.
 6. A coil winding arrangement as setforth in claim 5, wherein the tabs are formed in the gaps between thepole teeth.
 7. A coil winding arrangement as set forth in claim 6,wherein the crossover wires are adhesively bonded to the outstandingtabs.
 8. A coil winding arrangement as set forth in claim 7, wherein theadhesive bond is formed by an insulating material.
 9. A coil windingarrangement as set forth in claim 8, wherein the insulating material isapplied to the laminated plates before the winding and to the coils andcrossover wires after winding.
 10. A coil winding arrangement as setforth in claim 1, wherein the rotating electrical machine is athree-phase AC rotary machine and the number 3m of pole teeth is even,and coils of the same phase are wound on circumferentially adjacent m/2pole teeth and m/2 pole teeth at a symmetrical position in series, andwound in the opposite direction to each other corresponding to polaritychange of associated permanent magnets to which each pole tooth faces.11. A coil winding arrangement as set forth in claim 10, wherein thecrossover wires are adhesively bonded to the outstanding tabs.
 12. Acoil winding arrangement as set forth in claim 11, wherein the adhesivebond is formed by an insulating material.
 13. A coil winding arrangementas set forth in claim 12, wherein the insulating material is applied tothe laminated plates before the winding and to the coils and crossoverwires after winding.
 14. A coil winding arrangement as set forth inclaim 1, wherein the rotating electrical machine is a three-phase ACrotary machine and the number 3 m of pole teeth is 3×3×s, a multiple ofnine, and coils of the same phase are wound on adjacent m/3s pole teethat positions of the circumference divided into equal parts of 3s inseries, and wound in the opposite direction to each other correspondingto polarity change of associated permanent magnets which said pole toothface.
 15. A coil winding arrangement as set forth in claim 14, whereinthe crossover wires are adhesively bonded to the outstanding tabs.
 16. Acoil winding arrangement as set forth in claim 15, wherein the adhesivebond is formed by an insulating material.
 17. A coil winding arrangementas set forth in claim 16, wherein the insulating material is applied tothe laminated plates before the winding and to the coils and crossoverwires after winding.